1. Field of the Invention
The present invention relates to a stage apparatus, an exposure apparatus, and a method of manufacturing a device.
2. Description of the Related Art
In a conventional reticle stage of an exposure apparatus, only the non-patterned, limited portion of the lower surface of a reticle is chucked on a vacuum pad by vacuum absorption, so the vacuum pad often has an insufficient reticle absorption force. Thus, as the acceleration of the reticle stage is increased to improve the productivity, the reticle inertia force may exceed the reticle holding force (frictional force) by vacuum absorption, resulting in sliding between the reticle and the reticle stage. If the reticle position shifts upon such sliding, a serious problem that alignment may become impossible due to deterioration in alignment accuracy is posed. This limits the acceleration in scanning driving of the reticle stage, and therefore hampers an improvement in device productivity.
In order to solve such a problem, Japanese Patent Laid-Open No. 2000-299370 discloses an arrangement that holds a reticle by chucking its upper and lower surfaces by vacuum absorption.
Unfortunately, if a foreign substance adheres onto the upper or lower surface of the reticle, the following problem is posed. In projecting the pattern on the reticle surface onto a wafer, the precision of the pattern formed on the wafer deteriorates due to worsening of defocus within the pattern plane. Furthermore, the reticle may deform and warp upon clamping it due to the differences in flatness between the upper and lower surfaces of the reticle and the surfaces of members, which hold the reticle.